Arch or crown doors are decorative doors often used as cabinet doors, but which are also used as entrance doors. Such arch doors are normally of frame and panel construction, having a panel, the edges of which are received in grooves formed along the inside edges of a top rail, side rails, and a bottom rail which form the surrounding frame for the panel.
The visible portion of the arch is usually along the bottom edge of the top rail. The curve of the arch is a symmetrical compound arc curve with each lower end of the arch curving to become approximately tangent to a horizontal line perpendicular to the side edges of the rail, and the top of the arch at the center of the rail curves so it is tangent to a horizontal line spaced above the ends of the arch.
Where all the doors are of a predetermined width, or a number of doors the same width are required, as in factory made cabinets, the arch can readily be marked or cut in the top rail and the panel by using custom made templates or jigs for marking or cutting the contour of an arch of a desired height and width. A special jig or template is required for the top rail, and a different jig or template is required for the usually narrower panel.
In the past, for custom cabinets with arch doors, templates have been used for marking the rails and/or panels of the doors. Such templates may include templates for marking arches of a predetermined standard height on panels or rails of predetermined different widths. To obtain reasonable accuracy, it is necessary to have templates to mark the arches of panels for doors of one inch or so difference in width through a range of widths of the doors to be made, for example, 10 inches to 20 inches. This requires 11 templates for a width difference range of ten inches, where the arch is of a conventional or standard height.
If some standard templates are available the cabinetmaker can mark the shape of the arch on the panel, then cut the top of the panel to the shape of the arch. Since the panel is usually narrower than the rail, use of the same template to mark the rail requires very careful alignment to avoid marking a tilted or non-centered arch on the rail. Some cabinetmakers prefer to use the top edge of the panel as a template to mark the rail, (or the lower edge of the the rail to mark the panel, if the rail is cut first), but very careful aligning is again necessary since the panel is narrower than and usually somewhat thinner than the top rail. Further, with such templates the cabinet maker is restricted to a single arch height for a particular door width.
Templates for marking arches of different heights for the same door width would be quite desirable but the number of templates required would be the number of door widths times the number of different heights of arch. For example, 55 templates would be required for marking 5 different arch heights within the relatively small width difference range of ten inches. If the cabinet maker wishes to have such templates, he must make them, since there is no known source for such templates.
In much custom work, there is no standard width of cabinet, since the installation space determines the width of the cabinet, and the width of the cabinet determines the width of one or more doors of the cabinet, particularly in installations such as kitchen cabinets.
For custom cabinet work, the time required to layout and make a special template is not justifed. Where the door is of a non-standard width the cabinet maker can use either the next larger or smaller template, which is not quite accurate, and as a result the appearance of the finished cabinet is not wholly satisfactory.
Correspondingly, a disadvantage of templates is that a particular template is accurate only for its particular door width and arch height. Where the cabinet maker has such templates available, and needs to mark the arch of a panel for an odd size door, the marking is usually not accurate. Even where the marking is quite accurate, the required dimensions are compromised and the final product is not what was originally designed. Further, the problems involved in marking both the panel and the rail still exist, since a template for marking a rail is not satisfactory for marking the usually narrower panel and vice-versa.
In essence, when using templates for arch marking in custom cabinet work, an exact predetermined arch height is frequently not obtainable, for doors of many non-standard widths. Since a principle reason for custom cabinet work is to fit the cabinet to the available installation space, templates are simply not satisfactory.